Consistent treatment for pion form factors in spacelike and timelike regions

We write down some relevant matrix elements for the scattering and decay processes of the pion by considering a quark-meson vertex function. The pion charge and transition form factors F_π, F_πγ, and F_πγ* are extracted from these matrix elements using a relativistic quark model on the light front. We find that the form factors F_π and F_πγ in the spacelike region agree well with experiment. Furthermore, the branching ratios of all observed decay modes of the neutral pion that are related to the form factors F_πγ and F_πγ* in the timelike region are consistent with the data as well. F_π in the timelike region, which deals with the nonvalence contribution, is also discussed.